increase process priority instead of offloading to workers

Dockerfile

@@ -2,5 +2,6 @@ FROM node:current-alpine
 WORKDIR /app
 COPY package.json package-lock.json ./
 RUN npm install
-COPY . .
+COPY public ./public
-CMD ["node", "js/index.js"]
+COPY src ./src
+CMD ["node", "src/index.js"]

public/index.html

@@ -8,7 +8,7 @@
           "three": "/three/build/three.module.js",
           "three/addons/": "/three/examples/jsm/",
           "@tweenjs/tween.js": "/@tweenjs/tween.js/dist/tween.esm.js",
-          "stats.js": "/stats.js/src/stats.js"
+          "stats.js": "/stats.js/src/Stats.js"
         }
       }
     </script>

src/game.js

@@ -5,7 +5,6 @@ import Buff from './buff.js'
 import Entity from './entity.js'
 import Projectile from './projectile.js'
 import Terrain from './terrain.js'
-import { Worker } from 'node:worker_threads'
 
 export default class Game {
   id = crypto.randomUUID()
@@ -32,6 +31,10 @@ export default class Game {
   get tickBudget() { return this.#tickBudget }
   set logic(value) { this.#logic = value }
 
+  constructor() {
+    this.#eventEmitter.setMaxListeners(20)
+  }
+
   action(id, options) {
     const entity = this.entities.find((it) => it.id == id)
     if (entity == null) {
@@ -122,10 +125,6 @@ export default class Game {
   }
 
   subscription(websocket, id) {
-    const worker = new Worker('./src/worker/object-to-json.js')
-    const sendToWebSocket = function sendToWebSocket(message) { websocket.send(message) } // TODO: latency because workers wait for the main thread's next tick which is ~33ms
-    worker.on('message', sendToWebSocket)
-
     return function builtSubscription() {
       const game = this
 
@@ -136,7 +135,7 @@ export default class Game {
       const state = game.visionByTeam(team)
       state.currentTick = game.currentTick
 
-      worker.postMessage(state)
+      websocket.send(JSON.stringify(state))
     }
   }
 

src/index.js

@@ -1,7 +1,16 @@
+import { Dungeon, Ravine } from './level.js'
 import { WebSocketExpress } from 'websocket-express'
 import express from 'express'
 import Game from './game.js'
-import { Dungeon, Ravine } from './level.js'
+import os from 'node:os'
+
+try {
+  // WARNING: process.nice can undermine dependencies?
+  os.setPriority(process.pid, os.constants.priority.PRIORITY_HIGHEST)
+}
+catch (error) {
+  console.warn('Could not adjust process priority on startup.')
+}
 
 const app = new WebSocketExpress()
 const port = 1280
@@ -23,11 +32,13 @@ app.ws('/ws', async (req, res) => {
     const message = JSON.parse(rawData)
     console.log(message)
     if (message.action == 'join') {
+      const id = message.id
       websocket.send(JSON.stringify(game.joinReport()))
-      const subscription = game.subscription(websocket, message.id).bind(game)
+      const subscription = game.subscription(websocket, id).bind(game)
       game.eventEmitter.on('tick', subscription)
 
       websocket.on('close', () => {
+        console.log({ event: 'disconnected', id })
         game.eventEmitter.removeListener('tick', subscription)
       })
       return

src/worker/object-to-json.js

@@ -1,5 +0,0 @@
-import { parentPort } from 'node:worker_threads'
-
-parentPort.on('message', (message) => {
-  parentPort.postMessage(JSON.stringify(message))
-})

tools/fake-clients.js

@@ -0,0 +1,23 @@
+import WebSocket from 'ws'
+
+const numberOfClients = 10
+const url = 'ws://localhost:1280/ws'
+
+for (let i = 1; i <= numberOfClients; i++) {
+  const id = `${i}`
+  const websocket = new WebSocket(url)
+
+  websocket.onerror = () => websocket.close()
+  websocket.onopen = () => {
+    websocket.send(JSON.stringify({ action: 'join', id }))
+    console.log({ client: id, event: 'joined' })
+  }
+  websocket.onclose = () => {
+    console.log({ client: id, event: 'disconnected' })
+  }
+
+  websocket.onmessage = (event) => {
+    const byteSize = new Blob([event.data]).size
+    // console.log({ client: id, received: `${byteSize} B of data` })
+  }
+}